Toothbrushes generally have a plurality of bristle tufts, each tuft having a plurality of bristles, for removing plaque and debris from tooth surfaces. Typically, bristle tufts are configured for brushing the outer surfaces of the teeth, i.e., the buccal (cheek-facing), lingual (tongue facing), and occlusal (chewing) surfaces of the teeth. Dental floss is effective in removing plaque and debris from interdental or interproximal surfaces. However, not all individuals floss on a regular basis, and some individual hardly floss at all. Accordingly, it is desirable for toothbrush bristle profiles (the contour of the free cleaning/brushing/tooth-engaging ends of the bristles as seen from a side elevational view) to be designed to remove plaque and debris not only from the outer surfaces of the teeth but also from the interdental surfaces of the teeth.
Commercially available toothbrushes with flat bristle profiles (i.e., all free ends of the bristles are on substantially the same level or, in other words, are coplanar) clean the outer surfaces of teeth adequately, but are not always as adept at cleaning interdental surfaces and providing interdental stimulation as are toothbrushes with contoured bristle profiles (having free ends at differing heights). Various bristle profiles, such as a repeating “V”-shaped (aka, sawtooth or zigzag) profile, are known to increase the cleaning and gum-stimulating efficacy of toothbrushes.
Commercial toothbrushes typically have a brushing surface area (the surface area occupied by bristle free ends) of approximately 1 to 1.25 inches (25.4 to 35.8 mm) long and 5/16 to ⅜ inches (7.9 to 9.5 mm) wide. The bristles are generally arranged in 4 to 6 longitudinally extending (i.e., from the distal to the proximal end of the head, or, in other words, from the tip of the head towards the handle) rows of bristle tufts with 5 to 14 tufts per row, and approximately 20 to 50 bristles per tuft. Typical tufts are approximately 0.063 inches (1.6 mm) in diameter, with a cross-sectional area of approximately 0.079 inches2 (2 mm2). The diameters of commonly used bristles are: 0.006 inch (0.15 mm) for soft bristles, 0.008 inch (0.2 mm) for medium bristles, and 0.010 inch (0.25 mm) for hard bristles. The diameter of the bristles used in the brush, or increasing the tuft area, generally increases the stiffness of the bristles or tufts, and generally extends the life of the brush. However, such increases generally negatively affect the interdental cleaning of the brush, as well as the wear on the gums because the bristles are not as readily moved or bent to fit in the interdental spaces.
Accordingly, there is a continuing desire to improve the interdental cleaning ability of toothbrushes, especially since many individuals do not floss. Moreover, there is a desire to increases the life of the brush.